Well perforating device



July 3l, 195.6 n. 1. MCCULLOUGH WELL PERFORATING DEVICE 3 Sheets--Sheerll Filed OCt. 14, 1950 fr0 d. MCCU//ouy INVENTOR.

ATTORNEY July 31, 1956 J. MCCULLOUGH WELL PERFORATING DEVICE 3Sheets-Sheet. 2

Filed Oct. 14, 1950 fr0 L MCCU//ough INVENTOR.

@J4/AL ATTORNEY July 3l, 1956 J. MccULLOUGl-l WELL PEREORATING DEVICE 3Sheets-Sheet 5 Filed Oct. 14, 1950 IN VEN TOR.

fm d. MCcU//ough ATTORNEY United States WELL PERFORMING nevica Iray J.McCullough, Los Angeles, Calif., assignor to McCullough Tool Company,Los Angeles, Calif., a corporation of Nevada Application October 14,1950, Serial No. 190,105

'13 Claims. (Cl. IGZ- 20) This invention relates to devices employed inperforating the wall of a well bore and particularly to an improved formof` carrier employed to supportV explosive perforating charges of thehollow or so-called jet type during the operations of lowering suchcharges into a well bore, and'iring them after the carrier is in place,and which is thereafter retrievable from the well bore.

In the art of well perforating by means of explosive hollow charges, itis normally desirable to employ a multiplicity of perforating units,arranged generally longitudinally along a carrier, and which may be*tired, ordinarily simultaneously, or substantially so, to provide acorresponding plurality of perforations along the opposite section ofthe wall of the well bore. Various types of carriers have heretoforebeen employed which fall into two general classes, namely, recoverableand expendible. The recoverable type is ordinarily constructed in theform of a cylindrical steel body, which may be solid or hollow, andwhich is provided with a plurality of sockets, receptacles, or barrelsinto which the perforating units may bel inserted and protected againstintrusion of well uids by suitable sealing covers or caps. The severalperforating units are ordinarily connected to a suitable detonatingtrain which yextends through the interior of the carrier body. Carriersof this general type haveseveral disadvantages inthat they arerelatively expensive and complicated to construct, and althoughrecoverable, normally suffer considerable battering and damage by theexplosion of the charges, so that they may only be run a very few timesbefore they mustbe discarded or require extensive re-machining or repairbefore re-use. Also, they. are necessarily relatively rigid, heavy, andbulky and must be, of considerable length to support the. substantial.number of charges commonly employed for a single run, have onlyrelatively small clearance with respect to the wall of the well bore,and'consequently cannot be usedvto carry large. shaped charges in thewell bore. As a result, they are subject to becoming.V stuck in the wellbore, particularly where the latter is not straight or smooth, and oftenpresent diiculty in lowering and'in the recovery after tiring. Also, ifsuch bodies should become broken in the well bore, a not uncommonoccurrence, shing these broken parts out of the well may be very diicultor even impossible because of their size and mass.

Expendible carriers are of various types and may be constructed ofvarious metals, plastics, cement and the like, and may be made in solidor open-Work structural form, all of' which are designed to disintegrateor shatter under the explosive forces of the charges.y Such carriershave the principal disadvantage thatthe pieces resulting from theirdisintegration remain in the well bore where they may plug theperforations made by the charges and may have to be washed or lishedfrom the well borevto. clear the latter properly. Thus, in the case ofexpendable carriers, it isr highly desirable to provide constructionswhich will leave a minimum of so-called junk in thewell bore after use;

2,756,677 Patented July 3l, 19,56

Accordingly, the principal. objects of this. invention include theprovision of an improved form of carrier for hollow-type explosivecharges for insertion in awell bore, which will effectively support andpositionI any desired number of such charges; which will leave a minimumamount of junk in the well bore; which, is of exceptionally simple andcheap construction such that it may be expended in use; which, whileexpendable in the sense that it is not re-usable, is neverthelessrecoverable from the well bore; which permits use of charges of maximumdimensions for a given well bore diameter; which furnishes a positiveindication of the firing of the several charges; and which possesses ahigh degree of exibility-such that it may be readily lowered through,and removed from, well bores which are not perfectly straight andsmooth.

More specifically, the improved carrier in accordance with oneembodiment of this invention comprises a narrow elongated strip of flatmaterial, which mayk be relatively softand pliable metal, such asordinary aluminum, brass, copper, zinc, or steel sheet, having a widthsuch as to be readily insertible in the bore of a well. The side marginsof the strip may be re-inforced in any suitable manner, as by bendingthe edgesat right angles to the plane of the strip to form shortflanges; by rolling or crimping the edges to form beads thereon; or byrolling or crimping the edges around steel wires extendinglongitudinally along the side edges. Intermediate the edges of the stripand preferably along the center portion thereof, a plurality oflongitudinally spaced holes or openings is provided for mountingindividual perforating units which may be held in place by any suitablefastening means,y such as wire, clips, tape or the like. The upper endof the strip carrier is adapted for attachment to a lowering cable and afiring head for firing a detonating train which is strung along thecarrier and connected to the several charges. Weighting means of anysuitable form may be attached to the, car- Iier to assist in loweringthe devicethrough a well bore. The reinforcement of the edges of the,strip carrier prof vides additional tensile strength withoutsubstantially reducing the flexibility of the Strip, and forms exiblemembers which will bend or spread under transverse forces produced bydetonation of the charges without shearing, so that the entire stripcarrier remains suiiciently intact to be withdrawn from the well afterthe charges are fired. In order to further reduce they resistance to theshearing forces produced by the charges and to cause the strip topreferentially split or part. longitudinally intermediate the sideedges, the metal strip may be additionally weakened longitudinally alongits center portion in any suitable manner, as by removal of some of themetal intermediate the charge-supporting openings.

Other and more specic objects of this invention will become apparentfrom thefollowing detailed description when read in conjunction with theaccompanying draw.- ings which illustrate a useful embodiment of thisinvention. and several modifications thereof.`

In the drawings:

Fig. l isa front elevationall View of oneform of the carrier structurein accordance with this invention showing theV structure fully assembledwith the perforating charges preparatory to insertion in a well bore;

Fig. 2 isa longitudinal sectionalV view generally'along line Z-Zof Fig.1;

Fig. 3 is a cross-sectional view along line 3--3 of Fig. 2;

Fig. 4 is an elevational View of a strip carrierblank;

Fig. 5 is an endk Viewl looking upwardly toward" the lower endV oftheYcarrier'bl'ank'along line 5--5' of Fig: 4;

arene?? Fig. y6 isf a fragmentary View showing an arrangement v fvrmay'be'compressed by encircling thelatter withf a metal L f l l tor;cnnnectingtogethei-:two Camel-.Sections f lockingfband,aslshowng-which'may be oany suit- I 1' l z, 'f ',Fg. y7r visapian` viewyof a metalvclipshown positioned f rable :or conventional form: adapted.to -rmly fasten: neck -f f to; hold a-perforatng unit in place -on the'carrier; l f y23 to 'the firing' head, :to thereby attach the carriertothe f i l l Fig. -S, is afront elevation of fthe `metal clip looking f 5f head' and the lowering line.; A pair :ofscrews l l l along linei3d-8.0iligtf'; 1 l f l l f f f .f .f f f 2:39f-3'extendthrough-a pairlof holes? 31u-#31 ira-'opposite -f f Fig. 9 fis;r an elevationaly viewof =the clip; blank; 'f i v v f i f sidesiofineck'zsand screw intotheinsertedportion of itliie 1 l Fig.y 101s -afview of the assembledcarl-ier positioned f -f firing head to prevent relativerotation-between the carrier l f f 1 in: a well casingand yshowing ythe=carrier twisted 'about f f and h firing: head# -Fiiiug :head 29 iis'Connected 'to' the :its longitudinal axis yto alter the angularorientation` ot. 10 usual zlowering. cable lBld (Fig. 10'): by whichvthecarrier f f ille Porfofoiillg: Charge? i f v f f l may ybe lowered intoand'fwithdrawn `from ya'welli bore 1 f v Eig. ll- 'is'y a yfragrnentaryview of. they carrier which and: the` firing head may be provided withradially .arf f is rillustrative of. the condition of rthe'ca'rrierafter tiring' f f .rangedupwardlyand outwardlyfextending wire? ngers 23i i ofthe perforating units; t i 1 which may be :employedLinthefconventional. manner for'. Figs.v l2, y13 :and 14. arecross-sectional views ofy various` l5' positioning. the: carrier. inthewellf bore. f modieti ,Shapes in Whichfthecarrier may be constructed;:yf f l The =carrier isl adaptedrto support kexplosive :perforatl Fig.. l5isafragmeutary view, partly lin section, shot/vay ing units, designatedgenerally byy they numeralsg. which f ingy an alternative :arrangementyforl tiring the perior-atingvr are generally: tubular inform andpreferably of generally f .Charges mounted'on the carrier; and` f .i 1,f f i frusto-conical= external: shape.y Perforating units :of `,this r ff Fig.y 16 illustrates another means' by :which l they per-i .f type''are 7described;y iny detail kilu the S.y application of y foratingunitsmay be =fastened iin place ori-fthe 'fcarrieri. f William G.: -SweetmamrSeriali No.r y163,146,y tiled vMay f Referring erst ming. 4; the carrierin aecerdancewitn l 20,v 1950.l but theSpecicldetailsofsuchreroraringunits y .one embodiment gf; this inyentigny@Ornpyises ia. narrow' v r v ,do L noty form; apart of this invention,and only; the cx-v yelongated strip 2d constructed of arelatively-pliable sheet. l ternaglshape 'of outer casings '36 is'illustrated herein for f ,metaL such as ordinarysheetbrassy copper,vzinc, alu*= 2:5; the purposey of; showing the manner in which such`unitsminurm ,or steel, of any` suitable orl standard thickness, f maybei mounted lor supported on zthe carrier-= of: this' zSuch as,oneasixteeuth inch (0.36625),y i The widthi el? the i invention.. lItfshould he understood, however; thatsuch; 1 rstrip will: bemade;sornewhatless zthanf they diameter ofcafsings. contain: hollowedexpiosive :chargeswhich are de-k ithe well bore intowhichr it is toi beinserted." By:y Wella Sinflhdfupoli deioioiiou iofdiohai'go'aihig'hvolooiiy u'al' vhere?,itwill be understoodfthat reference is.hadto either i i row gaseous lietgeneraliy alone the f1'waitin-iina'1vHXS of:r f ;theguguai-pipegei-:Casing,employed i: line 'a weit bore: orl i the charge unitwhich perfonnsthedesired perforation. ofi ffitheuncased bore itsel.- The lengthofstrip mayibey f the wall'015thewellizvore.':zw-:1fz ==l- .'f. .f: v zany suitable; or desiredlength, -a 'f convenient length for -As shown particularly in .Figa yl:and; 2,: one oi the .f .f f rmost purposes Abeing about l2 feet@ Thevside margins: l units 35 :is yinserted yinto reach of :the: openings .22and;y f i `ofthe: strip 'are suitably reinforced by continuous pieces 35posiionell corXilly: heloius rtho vtalier :ofv ihr/ exteriori f ofstrong :steelwire .'21, suchias piano wiraiwhichare fas, off the casing:36 kserving to .lxnit; the' extent to which .f 2

f tenedy to'fthefstriprby rolling :or crimping'theedges: of thel theu-njtexterids:y throughithe yopening in accordance with f strip about'the lengths of wire..y The reinforcement-thus: the diameterzoftheopeningiZZ.. vtrdinarly; 'the casings'; i .provided for the feriges:y.of the metal strip. serves: to: im: 36 are provided withseriesofexternal annular shoulders= crease the' tensile estrength= of' fthe:carrier =and to :resist` 4D 3.7-2-37 increasingr in diametertoward thelarger end: ofl f transverse shearingfor parting stresses'which maybedethe casing. These shouldersl mayalso' serve as'abut'- veloped in thestrip. Wire of about 0.072 to 0.125 inch meIlS t0 engage the margin ofopening 22. The smaller in diameter, employed with aluminum strip aboutonethe diameters of holes 22, the greater will be the dissixteenth inchthick provides a construction which is tance which the discharge end ofthe perforating unit will found to be adequate in most cases. projectfrom the side of the carrier. As the perforating A plurality ofrelatively large diameter circular holes UIliiS are normally made ioStandardiled dimollSioXlS, the 22, are drilled or punched in strip 20generally along its diameter` of openings 22 may he Selected in lolailoncenter line and preferably on uniform center spacing, the thereto toProvide the desired degree of lateral proloospacing between holes 22being such as to provide the tion of the units relative to the face ofthe carrier. desired number of openings per foot 0f strip, for ex- 50Perforating units of the type illustrated will ordinarily ample, fourholes per foot on three-inch centers. be provided with an externalannular shoulder 38 adja- Smaller holes 24 may be drilled or punched 'inthe center Cent its discharge end. This may be employed forfastenportions of strip 20 intermediate adjacent pairs of the ing theunit in place on the carrier by means of metal larger holes 22 tothereby remove additional metal from ClipS 0f the form shownparticularly in Figs. 7, 8 and 9. the strip along its center, onepurpose being to addi- These clips comprise a circular band 39 adaptedto slip tionally weaken the strip generally along its center line Overthe discharge end 0f the perforating unit and Seat for purposes to bedescribed hereinafter. These smaller against shoulder 38. A pair of atmetal wings 40 exholes 24 also provide means for threading or windingtend from opposite sides of band 39 and are adapted to explosivedetonating cord therethrough in forming dethe hout rea-1W21l'dly toextend along tho SidoS of the onating connections to the severalperforating units, as Perfolaiirlg ullii and Pioleot ihlough Slots 25-25io will be described hereinafter. Narrow slots 25-25, the opposite faceof Strip 20- `The Projecting @uds of punched in the strip, are providedon opposite sides of wings 40 are then twisted, as at 41, in anySuitable each of the openings 22 for receiving the ends of the i mannerto lock them to the slots, the degree of twist means employed forfastening the explosive charges in boing Such aS to dlaW the uuitrearwardly iu opening 22 place in the strip, as will be subsequentlydescribed. lo thel'ehy hold it lightly iu Place ill the Slot either hySubstantiauy blank portions 26 and 27 are left at wedging action 0f thetapered Surface of casing 36 in the upper and lower ends, respectively,of the strip. opening 22 or by compression of shoulder 37 againstReferring now to Figs. l and 2, it will be seen that the the adjacentmargin of the openingupper blank portion 26 may be rolled or otherwisesuit- Alternate oueS of tho Poffofatiug units 35 may he iflably bentsymmetrically about its longitudinal center line Sorted from oppositedifeotions through openings 22, to form a generally tubular neck 2S forreception of the aS illustrated Particularly iu Figs- 1 and 2, theIoSuliug lower end of a generally conventional firing head, desig-Peffoatious heilig apart irl the Wall of tho Woll nated generally by thenumeral 29. The latter is adapted hofo- It Will he understood that allof the Performing to be inserted in neck 28 and is provided with anannular units may be faced in the Same direction, if desired, O1'

groove 32 into which the adjacent portion of neck 28 75 in any otherdesired arrangement. Fig. 10 illustrates avisas?? another manner inwhich the perforating units may be oriented, at diierent angles, aboutthe longitudinal axis of `the carrier. This is done by merely twistingthe carrier in any suitable manner about its longitudinal axis. Byvirtue of the ilexible construction of the carrier this may be veryeasily accomplished and will ordinarily be done by first mounting theunits in the manner illustrated in Fig. l and then applying the desireddegree of twist to the carrier.

The detonating train for the units comprises a continuous length offlexible detonating cord 42, such as the wellknown Prima Cord, whichextends along the length of the carrier and is trained successively overthe rear ends of the several perforating units in the manner asillustrated, for example, in Figs. l and 2, the cord passing alternatelyto opposite sides of the carrier through openings 24. The rear ends ofthe casings 36 may be provided with notches 43 to receive and retain thedetonating cord in proper detonating position over the ends of theunits. In the arrangement illustrated particularly in Figs. l and 2, thedetonating cord is tired from its lower end by means of a conventionalelectrically tired blasting cap 44 which is positioned adjacent thelower end of the detonating cord, to form a connection, designatedgenerally by the numeral 45. Electric current for tiring the blastingcap is supplied thereto by means of a conventional electrical lead 46which is strung along the face of the carrier and connects to anelectrode 47 which extends through the center of firing head 29,electrode 47 forming part of a conventional electrical conductor (notshown) which is threaded in the usual manner through lowering cable 34-and extends therewith to the surface where conventional electricalinitiating equipment (not shown) is located. Connection 45 formedbetween blasting cap 44 and the adjacent end of detonating cord 42 isenclosed within a suitable waterproof insulating jacket 48 which mayform a part of the connection, and this connection may be suitablyclamped to one side of portion 27 of the carrier, as by means of aU-bolt 49 which extends through openings Sil-50 provided in portion 27.The connection between the upper end of lead 46 and electrode 47 is alsowrapped and enclosed in a suitable water-proof insulating covering 51which may be shaped to be enclosed within the lower lend of neck 28 ofthe carrier, in a manner as illustrated p in Figs. l and 2. The upperfree end of detonating cord 42 is also enclosed in a water-proofwrapping 52 to protect it against intrusion of iluids which may bepresent in the well bore. It will be understood that detonating cord 42will also be encased within a suitable water-v proof, insulatingcovering such as rubber, or the like.

Fig. l5 illustrates a modified tiring arrangement by which detonatingcord 42 may be red from its upper end, rather than from its lower end.Either tiring arrangement may be employed successsfully with the carrierconstruction herein described for tiring the complete train ofperforating units.

While either the top or bottom tiring arrangement may be usedsuccessfully, it will generally be found to be preferable to use thearrangement for tiring the units upwardly from the bottom of the string.This tiring arrangement has the additional advantages that by ring thecharges from the bottom, if the carrier should, through some untowardcircumstance, part at the location of any particular charge, only theportion below this point, and from which the charges had been tired,would drop into the well bore, while the portion above the point ofseparation, containing the remaining charges, whether tired or unred,would be recoverable., The bottom ring arrangement, therefore, affordsan additional important measure of safety and assurance with respect toprotection of the well and the perforating device. This tiringarrangement may be applied with similar advantage to other and moreconventional types 6 y of perforating devices in which a series ofcharges are mounted for sequential tiring.

Since the weight of the carrier including the perforating units mountedtherein is relatively small, it may be found desirable in many cases toadd weight to the carrier in order to assure rapid and uninterrupteddescent of the carrier through the well bore, particularly where chargesin succession.

there is fluid present in the well bore, as is most often the case. Suchadditional weight may be applied in vari ous ways. One convenientarrangement is illustrated and consists of a pair of lead bars 53-53 ofgenerally semicylindrical form, which may be mounted on opposite sidesof portion 27 of the carrier and connected together by means or" bolts54 which pass transversely through the bars and portion 27. One ofthebars may be hollowed out to accommodate connection 45 and serves also'to protect this connection from striking projections which might bepresent along the well bore.

ln operation, the carrier having the perforating units mounted thereinand connected to ring head and lowering line in the manner illustrated,for example, in Figs. l and 2, is lowered to the desired point in thewell. Firing current will be supplied from the surface to blasting cap44 which will explode and set off detonating cord It?. which will, inturn, detonate each of the The intervals between the ring of thesuccessive perforating units will, of course, be extremely small so thatfor all practical purposes, their detonations occur substantiallysimultaneously. Explosion of perforating charges will completelydisintegrate the perforating units. it is a characteristic of welldesigned hollow perforating charges, that a portion of the forces of theexplosion will discharge from the hollowed end in the form of narrowgaseous jets along the longitudinal axis of the charge. However,substantial radial forces will also be developed and these will, ofcourse, act upon the edges of openings 22 surrounding the perforatingunits. By making the carrier of relatively thin sheet metal, asdescribed above, these forces tend to tear strip v2li apart,preferentially along its longitudinal center where the strip has beenweakened by the removal 0f the metal to form openings 22 andadditionally by the removal of intermediate portions of the metal informing holes 24. This results in what I have termed a can-opener eect,in that the carrier strip is split longitudinally, the reinforced edgesand the relatively Wider adjacent metal sections acting to effectivelyresist transverse shearing stresses so that the edge portions remainsubstantially intact and unbroken, although subjected to some degree ofbending. Fig. ll illustrates the general appearance of a portion of thecarrier after explosion of the charges. Upper and lower portions 25 and27 which have not been substantially weakened also remain intact andremain connected to firing head Z? through the unbroken edge portions ofthe carrier, with the result that, after the charges have been red, theentire carrier, together with the wires 21 will be withdrawn from thewell bore, along with the firing head and cable. Thus a very minimum ofjunk will be Ylett in the well bore.

lt will be noted from Fig. ll that the edges of holes 22 present abattered appearance, while the edges of holes 24, although torn apart,remain relatively smooth. The battered appearance of the holes in whichthe charges were originally mounted provides a very valuable indicationthat the perforating unit has, in fact, been detonated. When a string ofperforating charges is lowered in a well and tired, it is, of course,highly important that all of the charges should re. With moreconventional types of carriers heretofore employed, particularlyexpendible carriers, there was no practical way of determining whetheror not all of the charges had fired, since the carriers remained in thewell bore. yWith carriers constructed in accordance with the presentinvention, the carrier is not only recoverable, but is substantiallyintact except for the longitudinal split therein. Thus, merely by visualinspection of the carrier, after it is withdrawn from the well, a quickdetermination of the ring efficiency can be made.

Carriers in accordance with this invention have the additional advantagethat, by virtue of their narrow, at construction, they occupy aminimun-1 amount of space in a well bore and thereby permit utilizationof charges of maximum dimensions within the limits of the well borediameter. Their longitudinal and lateral ilexibility permits them to belowered in crooked well bores and through partially collapsed casing ortight places.

As noted, these carriers may be made in any desired length or made up ofsections connected end `to end to obtain a length suflicient to supportany desired number of perforating units. Fig. 6 illustrates one simpletype of connection between carrier sections in which the ends of twosections are simply over-lapped slightly and bolted together.

Fig. 16 illustrates another arrangement for fastening the perforatingunits in place on the carrier without using the previously describedmetal clips. In this modification, a unit is inserted in its supportingopening 22 and several turns of ordinary electrical tape S may bewrapped cir.

cularly about the carrier and the ends of the unit in the mannerillustrated to tie the two irmly together and retain the perforatingunit in the desired position. It will be understood that various otherconventional fastening arrangements may also be employed for thispurpose.

Figs. 12, 13 and 14 illustrate in cross-section other suitable shapesfor carriers constructed in accordance with this invention. In Fig. l2,the edges of strip 20 are merely turned inwardly and crimped to formreinforcing beads 56. In Fig. 13, the edges are shown double-crimped, asat 57. In Fig. 14, the edges are turned oppositely at right angles tostrip 20 to form oppositely extending edge anges 58. It will be obviousthat numerous' other arrangements may be successfully employed foreiectively reinforcing the side edges of strip 2 Generally speaking, thethickness of sheet 20 should oe the minimum commensurate with thestrength required to provide firm support for the perforating units. ItShould also be suciently rigid so as not to buckle or pile up when beinglowered into the well bore While, at the same time, it should besuliiciently flexible to follow a crooked or inclined or irregular bore.As noted, about one-sixteenth inch aluminum sheet is adequate for mostpurposes, although sheets somewhat thicker or thinner may besuccessfully employed. Such sheets will have sufficient tensile strengthto support whatever loads may be required in the ordinarycase and, ofcourse, reinforcement of the edges provides such additional tensilestrength, as may be required. Various other metals, such as copper,brass, zinc, soft iron, mild steel, and the like, having the desiredphysical characteristics and form, may be employed in the constructionof the carriers in accordance with this invention. Also, variousnon-metallic sheet materials, such as semi-hard rubber or plasticcompositions, and even suitably stifiened canvas or other fabrics may beemployed for construction of carriers in accordance with this invention.

By reason of the relatively simple construction of the carriers hereindescribed, it will be obvious that they may be constructed so that theymay be discarded after use with small economic cost. The tiring head andweighting members which are also recoverable can be re-used repeatedly.

It will be understood that various changes and alterations may be madein the details of this invention within t the scope of the appendedclaims but without departing from the spirit of this invention.

What I` claim and desire to secure by Letters Patent is: l. A wellperforating device, comprising, an elongated continuous strip ofrelatively thin sheet metal shaped to be longitudinally inserted in awell bore, a plurality of longitudinally spaced openings in the medialportion of said strip intermediate the opposite side edges thereofwhereby to provide longitudinally continuous marginal sections extendinglaterally from said openings to the side edges of said strip, anexplosive perforating unit of the hollow charge type xedly mounted ineach of said openings transversely to the plane of said strip, means forconnecting the upper end of said strip to a lowering means, and adetonating train extending longitudinally ci said strip in detonatingcontact with each of said perforating units. I

2. A well perforating device, comprising, an elongated continuous stripof relatively thin sheet metal shaped to be longitudinally inserted in awell bore, a plurality of longitudinally spaced openings inthe medialportion of said strip intermediate the side edges thereof whereby toprovide longitudinally continuous marginal sections extending laterallyfrom said openings to the side edges of said strip, continuousreinforcing elements `extending longitudinally along said marginalsections, au explosive perforating unit of the hollow charge type xedlymounted in each of said openings transversely to the plane of saidstrip, means for connecting the upper end of said strip to a loweringmeans, and a detonating train extending longitudinally of said strip indetonating contact with each of said perforating units.

i 3. A well perforating device, comprising, an elongated continuousstrip of relatively thin material shaped to be longitudinally insertedin a well bore, a plurality of longitudinally spaced openings in themedial portion of said strip intermediate the opposite side edgesthereof whereby to provide longitudinally continuous marginal sectionsextending laterally from said openings to the opposite side edges ofsaid strip, an explosive perforating unit of thehollow charge `type`ixedly mounted in each of said openings transversely to the plane ofsaid strip, means for connecting the upper `end of said strip to alowering means, and a detonating train extending longitudinally of saidstrip in detonating contact with each of said perforating units.

4. A Well perforating device, comprising, an elongated continuous stripof relatively thin sheet material shaped to be longitudinally insertedin a well bore, a plurality of longitudinally spaced openings in `themedial portion of said strip intermediate the side edges thereof wherebyto provide longitudinally continuous marginal sections extendinglaterally from said openings to the opposite side edges of said strip,an explosive perforating unit of the hollow ycharge type xedly mountedin each of said openings transversely to the plane of said strip, meansfor connecting the upper end of said strip to a lowering means, adetonating element extending longitudinally of said strip in detonatingContact with each of said perforating units and initiating meansconnected to the lower end portion of the detonatingelement whereby tofire said units sequentially upwardly from the lowermost one of saidunits.

5. A well perforating device, comprising, an elongated continuous stripof relatively thin llat sheet material shaped for insertionlongitudinally in a well bore, a plurality of longitudinally spacedopenings through the medial portion of said strip and spaced from theopposite side edges thereof whereby to provide longitudinally continuousmarginal sections of said strip extending laterally from said openingsto the side edges of said strip, reinforcing elements disposedlongitudinally along the side edges of both marginal sections, saidmarginal sections thereby having such structural strength that theirresistance to lateral shear is greater than the resistance of saidmedial portion to longitudinal splitting, whereby the strip may bepreferentially split longitudinally by the explosion of explosive unitsmounted in said openings, explosive perforating units of the hollowcharge type mounted in one or more of said openings in fixed positiontransversely to the plane of said strip, and a detonating trainextending longitudinally of said strip in detonating contact with eachof said perforating units.

6. A well perforating device according to claim wherein said material issheet metal approximately one-sixteenth inch thick, each of saidreinforcing elements comprising a side marginal portion of said stripwhich has been bent inwardly upon itself.

7. A Well perforating device according tokclaim 5 wherein said stripcarrying said units is twisted about its longitudinal axis to angularlyorient said charges rela tive to each other about said axis.

8. A well perforating device, comprising, an elongated continuous stripof relatively thin sheet metal adapted to be longitudinally inserted ina well bore, a plurality of longitudinally spaced openings in the medialportion of said strip intermediate the side edges thereof whereby toprovide longitudinally continuous marginal sections extending laterallyfrom said openings to said side edges, continuous reinforcing elementsextending longitudinally along said marginal sections, explosiveperforating units of the hollow charge type fxedly mounted in at leastsome of said openings transversely to the plane of said strip, means forconnecting the upper end of said strip to a lowering means, and adetonating train extending longitudinally of said strip in detonatingcontact with each of said perforating units.

9. A well perforating device, comprising, an elongated continuous stripof relatively thin sheet metal shaped to be longitudinally inserted in awell bore, a plurality of longitudinally spaced openings in the medialportion of said strip intermediate the opposite side edges thereof toprovide longitudinally continuous marginal sections extending laterallyfrom said openings to said side edges, continuous reinforcing elementsextending longitudinally along said marginal sections, an explosiveperforating unit of the hollow charge type fixedly mounted in each ofsaid openings transversely to the plane of the strip, strengthreliefmeans other than said openings in said medial portion of the stripintermediate said units, means for connecting the upper end of.saidstrip to a lowering means,

and a detonating train extending longitudinally of said strip indetonating contact with each of said perforating units.

10. A well perforating device according to claim 9 wherein each of saidreinforcing elements comprises said side marginal section bent inwardlyupon itself.

11. A well perforating device according to claim 9 wherein saidstrength-relief means comprise non-chargesupporting openings.

12. A well perforating device according to claim 11 wherein saidreinforcing elements comprise metal reinforcing wires secured to themarginal sections of said strip.

13. A well perforating device, comprising, an elongated strip ofrelatively thin sheet metal adapted to be longitudinally inserted in awell bore, continuous reinforcing elements disposed longitudinally alongthe side margins of the strip, a plurality of longitudinally spacedexplosive perforating units of the hollow charge type ixedly mounted inthe medial portion of said strip and extending transversely through thestrip, said strip being twisted about its longitudinal axis to angularlyorient said charges relative to each other about said axis, and adetonating train on the strip in detonating contact with the severalexplosive units.

References Cited inthe le of this patent UNITED STATES PATENTS 224,024Mason Feb. 3, 1880 386,535 Graham July 24, 1888 709,301 Capps Sept. 16,1902 928,344 Swahn July 20, 1909 1,346,283 Vierling et al. July 13, 19201,443,207 Blount Jan. 23, 1923 1,794,411 Lalumiere Mar. 3, 19311,962,608 McEachern June 12, 1934 2,026,061 Prikel Dec. 31, 19352,409,848 Greulich Oct. 22, 1946 2,412,011 Sanderson` Dec. 3, 19462,494,256 Muskat et al I an. l0, 1950 2,543,814 Thompson et al Mar. 6,1951

1. A WELL PERFORATING DEVICE COMPRISING, AN ELONGATED CONTINUOUS STRIPOF RELATIVELY THIN SHEET METAL SHAPED TO BE LONGITUDINALLY INSERTED IN AWELL BORE, A PLURALITY OF LONGITUDINALLY SPACED OPENINGS IN THE MEDIALPORTION OF SAID STRIP INTERMEDIATE THE OPPOSITE SIDE EDGES THEREOFWHEREBY TO PROVIDE LONGITUDINALLY CONTINUOUS MARGINAL SECTIONS EXTENDINGLATERALLY FROM SAID OPENINGS TO THE SIDE EDGES OF SAID STRIP, ANEXPLOSIVE PERFORATING UNIT OF THE HOLLOW CHARGE TYPE FIXEDLY MOUNTED INEACH OF SAID OPENINGS TRANSVERSELY TO THE PLANE OF SAID STRIP, MEANS FORCONNECTING THE UPPER END OF SAID STRIP TO A LOWERING MEANS, AND ADETONATING TRAIN EXTENDING LONGITUDINALLY OF SAID